<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <script src="js/vue.js"></script>
</head>
<body>
    <div id="app">
        <p>这个可以改变： {{ msg1 }}</p>
        <p v-once>这个将不会改变： {{ msg2 }}</p>
    </div>

    <script>
        var vm = new Vue({
            el: '#app',
            data: {
                msg1: 'Hello world!',
                msg2: 'Hello world!'
            }
        })
    </script>
</body>
</html>